guide me to write a capacity constraint

Question

I am trying to add few more constraint with existing  resource constraint project scheduling problem available OPL examples. Here I am attaching the example files of RCPSP problem. At present in this example problem I can start as many tasks as possible based on resource capacity. I want to add an additional constraint on maximum number of tasks performed in an interval variable should be less than or equal to 5. In other words simultaneously I can't do more than 5 tasks at a time.

The example problem can be located in OPL at examples/opl/sched_rcpsp

Answer 1

You could use cumul function.

Before the subject to block you could write:

cumulFunction nbTasks = 
   sum(t in Tasks) pulse(itvs[t],1);

And then in the subject to block you simply add:

nbTasks<=5;